Module 1.6.3 Physical Layer Quiz Answers
Network Addressing and Basic Troubleshooting – Module 1.6.3 Physical Layer Quiz Answers
1. What is an important function of the physical layer of the OSI model?
- It accepts frames from the physical media.
- It encapsulates upper layer data into frames.
- It defines the media access method performed by the hardware interface.
- It encodes frames into electrical, optical, or radio wave signals.
Explanation: The physical layer of the OSI model accepts frames from the data link layer and encodes it for transport as bits across the network media.
2. A network administrator is troubleshooting connectivity issues on a server. Using a tester, the administrator notices that the signals generated by the server NIC are distorted and not usable. In which layer of the OSI model is the error categorized?
- presentation layer
- network layer
- physical layer
- data link layer
Explanation: The NIC has responsibilities in both Layer 1 and Layer 2. The NIC encodes the frame as a series of signals that are transmitted onto the local media. This is the responsibility of the physical layer of the OSI model. The signal could be in the form of electrical, optical, or radio waves.
3. What is the purpose of the OSI physical layer?
- controlling access to media
- transmitting bits across the local media
- performing error detection on received frames
- exchanging frames between nodes over physical network media
Explanation: The physical layer is responsible for transmitting the actual signals across the physical media as bits. Exchanging frames, controlling media access, and performing error detection are all functions of the data link layer.
4. Which statement correctly describes frame encoding?
- It uses the characteristic of one wave to modify another wave.
- It transmits data signals along with a clock signal which occurs at evenly spaced time durations.
- It generates the electrical, optical, or wireless signals that represent the binary numbers of the frame.
- It converts bits into a predefined code in order to provide a predictable pattern to help distinguish data bits from control bits.
Explanation: Frame encoding converts a stream of data bits into a predefined code that is recognized by both the sender and receiver. These codes are used for a variety of purposes, such as distinguishing data bits from control bits, and identifying the beginning and end of a frame.
5. What is one advantage of using fiber-optic cabling rather than copper cabling?
- It is usually cheaper than copper cabling.
- It is able to be installed around sharp bends.
- It is easier to terminate and install than copper cabling.
- It is able to carry signals much farther than copper cabling.
Explanation: Copper cabling is usually cheaper and easier to install than fiber-optic cabling. However, fiber cables generally have a much greater signaling range than copper.
6. Which pairs of wires change termination order between the 568A and 568B standards?
- green and orange
- green and brown
- blue and brown
- brown and orange
Explanation: The difference between the 568A and 568B standards is the order in which the colored wire pairs are sequenced. It is the green and the orange pairs of wires that are swapped between the two standards.
7. What is the delay in the amount of time for data to travel between two points on a network?
Explanation: Latency is a term used to indicate delay when getting a packet from one point to another. Network connections with small amounts of delay are called low-latency networks, whereas network connections with long delays are called high-latency networks. High latency creates bottlenecks in any network communications.
8. What terms represent the maximum and actual speed that can be utilized by a device to transfer data?
- bandwidth; throughput
- throughput; bandwidth
- bandwidth; goodput
- throughput; goodput
Explanation: Bandwidth measures the maximum rate at which a device can transfer data. However, in practice, the actual speed for data transfer could be reduced because of numerous factors like network congestion, overhead etc. This actual rate of transfer is known as throughput.
9. Which type of network cable contains multiple copper wires and uses extra shielding to prevent interference?
Explanation: Shielded twisted-pair (STP) cables contain additional shielding and is commonly used when electromagnetic interference (EMI) or radio frequency interference (RFI) would negatively affect the data communication crossing a network cable.
10. What is line encoding?
- a method to represent digital information
- a security method used to protect data being transmitted
- a method to represent bits on the media
- a method to change the level of an electrical signal or optical pulse on the media
Explanation: Line encoding is a method of converting a stream of data bits into a predefined “code”. In other words, encoding is the method or pattern used to represent digital information.
11. What is a factor that determines the practical bandwidth of a network?
- physical media properties
- type of traffic
- amount of traffic
- latency caused by all intermediary devices
Explanation: A combination of factors influence the practical bandwidth of a network including the properties of the physical media as well as the technologies chosen for signaling and detecting network signals.
12. What are three options for signal transmission on a network? (Choose three.)
- radio waves
- vibration pulses
- sound waves
- electrical pulses
- light pulses
Explanation: There are three common methods of signal transmission used in networks:
- Electrical signals – Transmission is achieved by representing data as electrical pulses on copper wire.
- Optical signals – Transmission is achieved by converting the electrical signals into light pulses.
- Wireless signals – Transmission is achieved by using infrared, microwave, or radio waves through the air.